Study Area
Kerala is the second largest coffee-producing state in the country with predominantly Robusta cultivation in small holdings. The present study was conducted in the Regional Coffee Research Station (RCRS), Coffee Board, Chundale, Wayanad. RCRS is spanned in an area of 116.24 Ha Of wested forest land. The government of Kerala has handed over vested forest land to the Coffee Board, Government of India for the research and development of the coffee sector in Kerala.
Ant sampling techniques
Ants live in different strata of the ecosystem, as their nests vary from thick leaf litter to dead wood to modified nesting structures provided by plants, tree canopies, and soil. Concerning the above, ants cannot be collected by one technique, and hence different methodologies for collection were employed. Collection techniques employed to collect the ant fauna included pitfall traps, bait technique, transect- sampling, litter and soil extraction, Some ant species were photographed in the field itself.
Transect
A transect of 200 meters was selected for each sampling site
1. Litter Sifting
Leaf litter samples were sifted in a 1m x 1 m quadrant every 20 meters along the transect line using a litter sifter. Thus 10 samples were collected and sieved through a wire sieve with square holes of 1 cm x 1 cm and sorted and collected the ants in a jar containing 70% alcohol.
2. Soil core extract
Soil cores (20 x 20 x 15 cm) were taken at equal intervals (20 meters) along the transect. These soil cores were sifted through a hand sieve pan to collect ants.
3. Pitfall traps
Pitfall traps were placed in 1 meter away from the transect line on the opposite side s of the transect from where the leaf litter samples were taken. A plastic container consisting of 11 cm in diameter by 4 cm in height was placed in the hole with the lip of the trap level within the soil surface and was placed at 20 m intervals. The pitfall trap contains a small amount of soap solution to prevent the insect from escaping. The traps were kept open for 48 hours. Samples were collected and preserved in 70% ethanol and transferred to the laboratory for further identification.
4. Bait techniques
A small amount of sugar was placed in a Petri- dish which was placed 3 meters away from the transect line on the opposite side of the line where the soil cores were collected and left open for 20 minutes to capture ants. Thus 20 petri dishes are used to collect the ants from one site. After 20 minutes the contents were emptied into labelled polythene covers. This makes it easier to spot ants and capture them before they escape into the surrounding leaf litter.
5. Hand picking
This method is restricted to day hours (0900 hrs to 1300 hrs). Quadrates 5 m x 5m were marked along a line of transect in each 20 meters in the study area. Ants were collected from the marked quadrates immediately after bait trapping. Ants were collected using forceps, a moistened paint brush, and an inverted umbrella. The individuals are preserved in a jar containing 70% ethanol. Ants were transferred to the laboratory for further identification.
Ant morpho-species identification
For all sampling methods, ants were preserved in 70% ethanol and subsequently taken back to the laboratory for classification to species level and counting the number of species based on the morphology. Identification of ants into subfamilies, genera, species, or morpho-species was based on the keys by Bolton (1994), the specimens were also sent to the ant research labs of Punjab University, Patiala, and IISER, Bangalore, for authentication.
List of Species Collected from the Coffee Agroecosystem of the Wayanad Region of Western Ghats.
Sub Family
|
Genus
|
Name of the Species
|
Status
|
Formicina
|
Oecophylla
|
Oecophylla smaragdina
|
1
|
Camponotus
|
Camponotus Parius
|
7
|
Camponotus irritans
|
Camponotus singularis
|
Camponotus radiatus
|
Camponotus sericeus
|
Camponotus angusticollis
|
camponotus compressus
|
Anoplolepis
|
Anoplolepis racillipe
|
1
|
Paratrechina
|
Paratrechina longicornis
|
1
|
Polyrhachis
|
Polyrhachis rastellata
|
5
|
Polyrhachis Exercita
|
Polyrhachis wroughtonii
|
Polyrhachis tibialis
|
Polyrhachis puctillata
|
Lepisiota
|
Lepisiota opaca
|
1
|
Nylanderia
|
Nylanderia yerburyi
|
1
|
Dolichoderinae
|
Technomyrmex
|
Technomyrmex albipes
|
3
|
Technomyrmex bicolor
|
Technomyrmex elatior
|
Tapinoma
|
Tapinoma indicum
|
2
|
Tapinoma melanocephalum
|
Ponerinae
|
Brachyponera
|
Brachyponera lutipes
|
2
|
Brachyponera Jerdoni
|
Leptogenys
|
Leptogenys diminuta
|
3
|
Leptogenys birmana
|
Leptogenys processionalis
|
pseudoponera
|
Pseudoponera
|
1
|
Diacamma
|
Diacamma ceylonese
|
2
|
Diacamma rugossum
|
Odontomachus
|
Odontomachus simillimus
|
|
Odontomachus haematodes
|
2
|
Harpegnathos
|
Harpegnathos saltator
|
1
|
Myrmicina
|
Crematogaster
|
Crematogaster rogenhoferi
|
3
|
Crematogaster abberans
|
Crematogaster walshi
|
Myrmicaria
|
Myrmicaria brunnea
|
1
|
Pheidole
|
Pheidole sps 1
|
2
|
Pheidole sps 2
|
Monomorium
|
Monomorium wrouhtoni
|
2
|
Monomorium indicum
|
Carebra
|
Carebra diversa
|
1
|
Tetramorium
|
Tetramorium coonoorense
|
2
|
Tetramorium walshi
|
Solonopsis
|
Solonopsis germinata
|
1
|
Meranoplus
|
Meranoplus bicolour
|
1
|
Cataulacus
|
Cataulacus kaprobanae
|
1
|
Dorylinae
|
Dorylus
|
Dorylus orientalis
|
1
|
Pseudomyrmecinae
|
Tetraponera
|
Tetraponera allaboras
|
3
|
Tetraponera nigra
|
Tetraponera rufonigra
|
During the study period, a total of 5311 ants were collected, representing 51 species in 26 genera and six subfamilies. The distribution of species in the different subfamilies showed a dominance of Formicinae with seventeen morphospecies (32%) followed by Myrmicinae (28%), Ponerinae (22%), Dolichoderinae (10%), Pseudomyrmecinae (6%) and Dorylinae (2%). The subfamily Myrmicinae exhibits dominance in genus richness, with 9 genera, followed by Formicinae (7 genera) and Ponerinae (6 genera).
The most diverse ant genus is Camponotus, with 7 named species, followed by Polyrhachis (5 species), the genus Leptogenys,Tetraponera, Technonomyrmex, Crematogaster, represented by 3 species each, and Tapinoma,Brachyponera, Pheidole,Diacamma, Odontomachus, and Tetramorium, represented by 2 species. Only one species is recorded from the genus Myrmicaria, Oecophylla, Anoplolepis,Paratrechina, Lepisiota,Nylanderia,Pseudoponera, Carebra, Solonopsis, Meranoplus,cataulacusk, and Dorylus. Two monotypic exotic genera, Anoplolepis and Paratrechina, were recorded in this study. Most of the ant species found in this study have been reported as generalized foragers and predators. Two general foraging groups arboreal and ground ants are reported in this study. The highest species abundance was reported in moderately shaded coffee plantations, followed by shaded and the least in openly shaded coffee plantations. The moderately shaded coffee plantation has optimum temperature, humidity, and tree connectivity for ant activities compared to the thick and open shade. Filter shade and litter increase the availability of nesting sites and foraging areas. The rank abundance for the shaded, open, and moderately shaded coffee plantations revealed that the highest abundance was that of the species Tapinoma melanocephalum. Crematogaster rogenhoferi Technomyrmex albipes, and Oecophylla smaragdina, are the most abundant species. Pit fall trap is the most effective sampling technique. 1757 individuals are collected through the pit fall trap method (32%). The second most efficient method is the transect method (28%). Soil core extraction (4%)is the least efficient method compared to all other techniques.